The execution type of your order depends on your account type.
In general, all CFD accounts use the so-called Market Execution, while the Invest account type uses the Exchange Execution.
The two types of execution are defined as follows:
With this type of execution, the execution of your order is guaranteed, at the next available price. This means that no additional confirmation of the execution price is required. This execution type is considered the fastest of all execution types. However, the price at which the order is executed depends on the market situation and there is no guarantee of the execution price.
In this mode, trades made on a platform are routed to an external trading venue. The orders are executed at the current prices of that market. The execution of your order is not guaranteed and may be rejected in the event of major price deviations or insufficient liquidity.
Execution methods should not be confused with fill methods for orders. You can find out more about fill methods here.